题目内容：
请根据短文的内容，回答题。 Centers for Disease Control
One of the major health agencies in the United States is the Centers for Disease Control and Prevention. It is known as the C-D-C. "Prevention" was added __________ (51) the name later. The agency has many jobs. For example, it recently __________ (52) information to the public about ricin (蓖麻毒素) . Some of that poison had been found in a Senate office building in Washington. The C-D-Cadvised people about ways to stay __________ (53) if they ever found ricin.
The C-D-C warns, advises and reports on health subjects from around the world. For example,it is currently providing information about avian influenza. The __________ (54) of bird flu in Asia has killed more than twenty people in Thailand and Vietnam.
The agency also is advising people __________ (55) to protect against cold weather and__________ (56) heated homes in winter. And the C-D-C just gave Americans the newest estimate of how long they can expect to __________ (57). In two-thousand-two, average life expectancy reached seventy-seven-point-four years. __________ (58) the C-D-C also reported an increase in the rate of deaths among newborn babies that year. It was the first__________ (59) in the United States since nineteen-fifty-eight.
The Centers for Disease Control and Prevention is an agency within the Department of Health and Human Services. Its main offices and laboratories are in Atlanta, Georgia.
Eight-thousand-five-hundred people work __________ (60) the C-D-C. These __________ (61)doctors, nurses, scientists, engineers and others. They all have some part in trying to learn how diseases start, and where and how they spread.
C-D-C laboratories examine tissue, blood and other substances to help __________ (62) diseases. For example, the C-D-C recently confirmed the presence in Bangladesh of a viral infection similar to the Nipah virus. This virus was first recognized in nineteen-ninety-nine in Nipah, Malaysia. It was __________ (63) widespread cases of encephalitis (脑炎), a brain infection. More than one-hundred people __________ (64) the disease.
C-D-C experts are __________ (65) to travel anywhere in the world to help deal with
outbreaks of disease. The faster the cause is identified, the faster health workers can take steps to contain and control it.
__________ A．on
B．in
C．upon
D．to
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